Force field (chemistry)

For other uses, see Force field (disambiguation).

A force field is used to minimize the bond stretching energy of this ethane molecule.

In the context of molecular modeling, a force field refers to the form and parameters of mathematical functions used to describe the potential energy of a system of particles (typically molecules and atoms). Force field functions and parameter sets are derived from both experimental work and high-level quantum mechanical calculations. "All-atom" force fields provide parameters for every type of atom in a system, including hydrogen, while "united-atom" force fields treat the hydrogen and carbon atoms in methyl and methylene groups as a single interaction center. "Coarse-grained" force fields, which are frequently used in long-time simulations of proteins, provide even more crude representations for increased computational efficiency.
The usage of the term "force field" in chemistry and computational biology differs from the standard usage in physics. In chemistry it is a system of potential energy functions rather than the gradient of a scalar potential, as defined in physics.